Question

鸸鹋 Elmer 在乡村道路上相邻两根电线杆之间行走需要 $44$ 个等长步幅。鸵鸟 Oscar 用 $12$ 个等长跃步可以走完同一距离。电线杆等距排列，这条路上的第 $41$ 根电线杆距离第一根电线杆正好一英里（ $5280$ 英尺）。Oscar 的一个跃步比 Elmer 的一个步幅长多少英尺？

Elmer the emu takes $44$ equal strides to walk between consecutive telephone poles on a rural road. Oscar the ostrich can cover the same distance in $12$ equal leaps. The telephone poles are evenly spaced, and the $41$ st pole along this road is exactly one mile ( $5280$ feet) from the first pole. How much longer, in feet, is Oscar's leap than Elmer's stride?

$6$

$8$

$10$

$11$

$15$

答案：B

知识点：植树问题比与比例

难度评级：1270

解答：

第一根和第 $41$ 根电线杆之间有 $40$ 个间隔，所以每个间隔长 $\dfrac{5280}{40} = 132$ 英尺。

Elmer 的步幅为 $\dfrac{132}{44} = 3$ 英尺，Oscar 的跃步为 $\dfrac{132}{12} = 11$ 英尺，差为 $11 - 3 = 8$ 英尺。

所以正确答案是 B。

There are $40$ gaps between the first and $41$ st poles, so each gap is $\dfrac{5280}{40} = 132$ feet.

Elmer's stride is $\dfrac{132}{44} = 3$ feet and Oscar's leap is $\dfrac{132}{12} = 11$ feet, a difference of $11 - 3 = 8$ feet.

Thus, the correct answer is B.

2021 AMC 12A Fall 第 5 题

答案：B

难度评级：1270

解答：

其他年份的第 5 题